Telephone system



1,696,267 B. G. DUNHAM TELEPHONE SYSTEM Dec, 25, 192s.

Filed June 1s, 192'. 2 sheets-sheet 1 v FEEL-@m :gli

WNW

Patented Dec. 1928.

UNITED STATES PATENT oFFlcE.

BERT G. DUNHAM, OF HAWTHORNE, NEW JERSEY, ASSIGNOR TO BELL TELEPHONE LABORATORIES, INCORPORATED, 0F NEW YORK,

YORK.

N.' Y., A ooRroRATIoNro'r NEW TELEPHONE SYSTEM.

Application med June 13, 1927. semina. 198,487.

This invention relates to telephone systems and particularly Ato circuit arrangements for switches used in automatic telephone systems.

It is applicable to the circuits for selector and connector switches of any well-known step-by-step type. K

A feature ot' this invention is an arrangement whereby a relay is fully operated during the vertical selective movement oit' the selector to prevent the rotary hunting movement from taking place and partially perated when the vertical'V movement ceases to provide a pulsing circuit yfor the rotary hunting movement. l

Another feature of this invention is a con nector circuit in Which theusual ringing rew lay is also employed for actuating a socalled permanent signaP7 the moment thel connector is seized. This relay is also used i to guide the selective impulses into the vertical magnet or into the rotary 1nagnet as required. In case the connector is limiting for an idle private branch eX- change trunk and all trunks in the group are busy this relay serves to stop the hunting action of the connector on the terminals of the last. trunk in the group. The usual busy test relay ot' the connector is also employed in conjunction With the rotary magnet for producing the hunting movement of the conncctor.

This invention has been illustrated in the accompanying drawings in which l shows a selector circuit and F ig. 2 shows a connector circuit embodying the features of this invention.

Referring to the drawing, a description i will be made ot' the extensionotl a connection through the selector and connector from a calling subscribers line `that may be associated through any Wellsknown line finder circuit with the trunk conductors 2. This connection may be extended through the connector to subscribers lines terminating in the group ot' terminals shown at` 100 or to prifate branch exchange trunks terminating in the group ot terminals shown at lOl. shouldbe understood that any Well known step-by-step selector and connector switches may be employed in connection with these circuits and no attempts have therefore been made to illustrate them, except in diagrammatic term.

. to ground. ITheresistance characteristics ol relay 4 and vertical magnet 5 are such that If it is assumed that the calling'subscribers line has' been extended lto the conductors at 2 a connection will be completed through the calling'subscribers dialing loop to battei-y and groundthrough theavindings ot. relay 3. Relay 3 will thereby operate to close a circuit for the operation of the sloW to release relay it as olloWsz' battery, Winding ot vertical magnet 5, Winding of relay It, armai ture and front contact of pulsing relay 3 the vertical magnet Willnot operate in this circuit. Relays in operating'closes alcole ing circuit forv itself, through its inner lefthand armature and front Contact to ground With the battery suppliedthrough the vertical magnet k5. This relay l in operating also connects the sleeve conductor from the line Vtinder to ground at the outer left-hand armature to maintain the connection as is WellknoWn in the art.

It now the calling 'subscriber actuates his dial to select a Wanted subscriber-s line, relay 3 Will be alternately released and operated in accordance With the impulses of the iii-st digit. The first release of the relay 3 closes a circuit for the operation of the vertical magnet 5. This circuit may be traced from battery through the Winding ofthe Vertical magnet, right-hand winding otrelay 6, armature and back vcontact of pulsing `relay 3, to ground at the inner left-hand armature and front Contact of relay 4. The vertical mag- Vnet now takes the first step to advance the brushes 8 towards the desiredgroup of connector terminals. Relay 6 `also .operates and as it is Slo7 inreleasing it will remain operated during the pulsing of relay 8. Relay 4 is also slow to release so that it will remain operated during the operation of the relay 3 in response to the dialing.` It should be noted that this latter relay will actually be locked in operated position a't'ter the operation of the pulsing relay eventliough the armature et the pulsing relay may not be connected to the ground at its inner contact during the pulsing. 'Relay 4 releaseswhenthe pulsing relay releases its armature to connect t leases due to the operation of relay l2 as will hereinafter be described. Hence the maintaining of relay l operated during dialing does not depend on the repeated closure of a circuit through the armature and front contact of the pulsing relay as is the case in ordinary pulsing relay and slow to release relay circuit combinations. The advantage ot this arrangement is that the pulsing relay need not become fully operated by the dialing pulses, a condition that may be due to unusual line attenuations which in ordinary cases would interfere with the proper functioning of the selector circuits.

The operation oi the vertical magnet :'i in response to the dialing is due to short circuiting of the winding of relay JlA each time the pulsing relay is released. This circuit for operating the vertical magnet may be traced as follows: battery, winding ot vertical magnet 5, winding ot relay (3. armature and back contact of pulsing .relay il to ground at the inner left-hand armature and front contact ot' relay el. The repeated oynration of the vertical iagnet 5 advances the brushes 8 of the selector to the desired level where, hunting tor the terminals ot an idle connector may begin through the` operations ot the rotary magnet 9.

To cause the switchv to hunt for an idle connector` circuits Will be closed for the rotary magnet on the partial release of relay (S after the last impulse of the first digit has been received. At this time the circuit through the right-hand Winding of relay (l will be opened at the armature and back contact of relay Besides beingslow to release the operating characteristics ot relay (3 are such that it will only partially release at this time due to the tact that a circuit is closed through its lett-hand Winding as follows battery, left-hand winding of relay 6, righthand armature and back contact ot rotary magnet 9, armature and back contact of rclease magnet l0, inner left-hand armature and front contact of relay 4T lo ground. lith relay 6 in this condition a connection will be established through the armature and malre-hetore-break contacts ot' this relay to close a circuit tor the rotary magnet 9 as follows: battery, winding of rotary magnet 9, arn'iature and inake-before-break contacts of `relay 6, the operated vertical olf-normal conconnection.

lninal of this connector which will prevent relay l2 from operating. lt will he noted that on the operation oi. the rotary magnet 9 an energizing circuit is closed for the opera tion of this relay l2 as follows: batterjf, resistance 13, left-hand armature and front contact of rotary magnet 9, 11th step rotary contacts 14, winding of relay 12, outer letthand armature and front contact of relay l to `ground. The Winding ol' relay l2, how ever, is now short-circuited due to the ground from the sleeve terminal ot the busy conne tor. This ground being connected through the sleeve brush of the selector brushes S, the, second left-hand lower armaturev and back contact of relay 12, contacts ll, armature and front contact of rotary magnet 9 resistance 13 to battery. As relay l2 is not operated the rotary magnet will again operate to advance the brushes 8 to the terniinal ot the. next conncctor. Then therefore the rotary magnet 9 releases, as hercinbelore described, the circuitthrough the lett-hand winding oi relay (l is again closed. Relay (i will operate suliiciently to establish a` connection through its armature and inalie-before-brcalr contacts for the original energizing circuit for rotary magnet 9, so that this` magnet will now again be operated to advance the brushes 8 to the terminals of the next connector. These 'functions or" the rotary magnet and relay (l will continue until the brushes 8 have found the terminals of an idle connector. It; will be seen from this description that the ground on idle sleeve need not be a direct ground but may be a ground through a resistance, as all it is required to do is to prevent relay l! from operating. This arrangement is of ad vantage as the selector may he used with connector circuits having dill'erent ground characteristics on their sleeve terminals.

lVhcn an idle connector is found the above mentioned shortscircuit to prevent relay lt! from operating will not he eiuountcrml as l he Sleeve of the idle connector has no ground Relay 'l2 will therefore non' operate through the above mentioned circuit which is completed from battery at the lc'thand armature and front contact oi rotary magnet 9 and the ground at the. outer left hand armature and front contact ol rela-y il. The arrangement ol the armatures ol relay l2 is such that the armature 'l5 closes with its front contact before conuccliom are Juade through any of the other liront contacts. Thus, a circuit will immediately he couxpleted from battery through the winding of the rotary magnet 9, armature. l5 and its cor responding front contact, winding ol relay l2 to ground at the outer left-hand arma In ture and front contact ot relay 4.

This circuitwill then produce, due lo the removal of the ground connection througli the sleeve, a momentary inductive kick or rise in the energizing current tor relay l2 so that this relay will now be quickly and fully energized to pull up the remaining armatures. In other words, relay 12 will be quickly energized after the brushes 8 land on the terminals of an idle connector; Relay 12 is held operated under control of rela-y 4, and the ground, through the outer left-hand armature and front contact of relay 4, will be extended through the second lower armature and front contact ot' relay 12 to rthe sleeve brush of the group 8 of the selector and the sleeve terminal of this idle connector to make it busy to other selectors. y

The operation of relay 12 also opens the circuit from the calling subscribers loop through the windings ofrelay 3 and extends this connection over the'tip and ringvcofn- ,ductors from the subscribers loop through to the tip and ring conductors of the associated connector. A circuit will thereby be completed for the operation of relay 102 as follows: battery, left-hand winding of relay 102, lower outer make-before-break Contacts of relay 103, ring conductor of the associated connector, its' ring terminal, the ring brush of the group 8, the lower inner armature and front Contact of relay 12, ring conductor'through the calling subscribers loop back to the tip conductor, the upper armature and front Contact of relay 12, tip brush o the group 8tipterminal of the associated connector, inner make-before-break contacts of relay 103, right-hand winding of relay 102 to ground. Relay 102 in operating closes a circuit for the operation of the slow to release relay 104 as follows: battery, winding of relay 106, armature andfront contact of relay 102, winding of relay 104, to ground and also from battery, through the winding of rotary magnet 115, lower middle armature and back contact of relay 105, lower third armature and back contact ot' relay 112, armature and front contact of relay 102 and winding of relay 104 to ground. Tliefoliierating characteristics of relay 106 and magnet 12 are such that they will not be actuated in this circuit. Relay 104: in operating closes a circuit to ground forthe sleeve conductor toL the sleeve terminalof this connector so that this ground connection will now extend over the' sleeve terminal, the sleeve brush of the group 8, and the second lower armature and front contact of relay-12 to provide a substitute holding ground for the relay 12. This holding circuit is necessary as the original holding circuit controlled by relay'et is broken soon after the operation of relay 12. That is, the operation of relay 12 causes the release of relay 3 and this" relay in releasing closes a short-circuiting connection for relay et from battery, winding of vertical magnet 5, winding of relay 6, and` armature and back contact of relay 8 to ground at the inner lefthand armature and front contact of relay 4. Relay i is thereby released to open this original holding circuit for the rotary magnet 9 and relay 12, butthe slow to release characteristic of relay 4l allows sufficient time for the new holding circuit to be closed beorethis original circuit is opened. The busy ground for the line finder will now therefore be supplied from the middle right-hand armature and front contact of relay 10st as it should be noted that the sleeve conductor from the line hn der is connected to the second lower armature and Yfront Contact of relay 12 to this ground. This vground will of course also serve as a busy ground for the connector.

Y The operation ot relay 104.- as liereinbetore mentioned closes a circuit for the operation yof relay 105 as follows: battery, upper winding of relay 105, middle normally made contracts ot' the Vertical oil-normal contacts 107, inner right-hand armature and frontcontact of relay 10sL to ground.` The connector circuit is now ready for the reception of impulses tol actuate it to select a-wanted subscribers line. lt should be noted that a circuit for lighting the permanent signal 108 is completed when relay 105 actuated as follows: battery, signal 106, inner right hand armature and bach Contact of relay 106, inner lower armature and 'frontcontact ci relay 105, inner lower armature/and back contact oit' relay 10S to ground. This signal 108 is generally called a permanent signal and is located in a convenient placev for inspection purposes. That is, if the calling subscriber yabandons Vthe call at this stage or does not dial within a certain period, this signal will indicate to an inspector the switch involved in this connection. If the subscriber dials within that period this signal will be extinguished at the proper time, namely when relay 106 is operated as will be described hereinafter. It the wanted subscribers line terminates in contacts in bank 100 the brushes 110 will be advanced to this level by the vertical movement of the switch and then rotated by the rotary movement of the switch over this terminal bank until the terminals oi!V the desired lines are found'.

The pulsing relay 102 will be alternately released Vand operated in accordance with the `second digit to cause the advance of the brushes to the bank 100. On the first release of relay 102 a. circuit is closed for the operation of relay 106 and the vertical magnet 111. The circuit for thevertical magnet may be traced from battery through the winding oi' 1 the vertical magnet, middle lower armature and front contact ol' relay 105, third lower armature and back Contact of relay 11,2, outer right-hand armature and liront contact olf relay 104,' make-before-break contacts oli relay 102 to'ground. The circuit for relay 106 may be traced from battery th rough the winding oi' this relay to the same ground at the make-before-breal contacts of relay 102. Relays 104 and 106 are slow to release so that they will remain operated during the pulsing, while the vertical magnet will respond to the pulses. rlhe operation of relay 106 opens the circuit tor signal 108 so that this signal will he extinguished when the dialing begins. It will be noted that on the first step of the brushes 110, the vertical olf-norn nial contacts 10T will be opened and thus cause the original energizing circuit t'or relay 105 to be opened. n. locking circuit for relay 105 is, however, provided through contacts of relay 100 over a circuit as follows battery, upper winding ot relay 105, upper inner armature and trout contact, olf this relay, inner right-hand armature and front Contact of relay 100, lower inner armature and front contact o1 relay 10.1, lower inner armature and back contact ol relay 10i-l to ground. When the bank 100 has been reached the vertical magnet 111 and relay 10G will release, and the release of 100 releases relay 105.

A circuit is now completed :for the rotary magnet 115 on the tirst impulse of the last digit as l'ollows: battery, winding` and rotary magnet 115, lower middle armature and back Contact of relay 105, third lower arinature and hack contact ot relay 112, outer right-hand armature and front contact ot' relay 101, inalie-before-break contacts ot relay 102 to ground. The hereinbet'ore traced circuit for relay 10G is also completed at this time. The rotary magnet will now respond to the impulses of the last digit and advance brushes 110 to the terminals of the desired line. It should he noted that when the vertical olf-normal contacts 10T were operated an obvious circuit was completed through the left-hand winding ot relay 110 so that this relay is operated at this time for a purpose as will hereinafter be described.

f the desired line is busy a connection to ground will be made through the brush S 'from the corresponding brush ot the connector engnlaging` the corresponding terminal of this busy line. This closes a circuit for the operation of relay 118 and this circuit will he closed before relay 106 has time to release after the last rotary impulse is received. This circ-uit inay be traced as follows: battery, winding ot relay 118, armature and hack contact of the rotary magnet 115, third upper armature and hack contact ol relay 112, upper outer armature and bach contact of relay 105. outer right-hand armature and lront contact. ol: relay 100, to ground on the S brush. lelay 118 is locked in operated position over the 'follf'iwing circuit: battery, winding of relay 118, armature and back contact of rotary magnet 115.` third upper armature and hack contact ot' relay 112, inner left-hand armature and front Contact ot' relay 118, middle right-hand armature and front contactof relay 101 to ground. When relay 106 is released the connection from ground on the S brush is opened at the outer right-hand armature and front contact of this relay so that when the connector releases as will hereinafter be described, there will he no connections through any relay from the brush S and consequently the circuits of this connector cannot be disturbed from grounds on the corresponding terminals ot other busy lines as the brush b' of this connector in returning to normal passes over these busy terminals. The operation of relay 118 l'uovides a busy tone tor the calling;1 subscriber, the circuit for which may be traced as follows: l'roln ground through the left-hand winding; of the repeating coil 120, the right-hand windingr of which is connected to a. suitable ringing; source, through the outer right-hand armature and Ji'ront contact of relay 11u, tip conductor of the connector, through the condenser 1122 to the tip conductor over the selector ol" Fig. 1 to the calling subscribe1"'s line.

It the desired line is not busy relay 100 releases and relay 118 will not operate. llelay 112, however, will be operated over a circuit as follows: battery, windil'ig ol' the usual rut@ ott relay (not shown) ot' the wanted sub scrihers line, through the sleeve terminal ol' this line, sleeve hrush S, outer riul'it-hand armature and hach contact of relay 100, lower winding of relay 112, inner left-hand armature and Yfront Contact o relay 11G, inner lett-hand armature and back contact of relay 118, niiddle right-hand armature and front contact of relay' 104 to ground. Relay 112 in operating provides a looking circuit for itself as follows: battery, upper windingl of relay 112, second upper arn'iature and trout contact of relay 112, inner right-hand armature and front Contact of relay 101 to ground. The operation of relay 112 provides` a direi-t ground connection at its second lower urinature and front contact for the brush S to operate the cut-oil relay to disconnect battery and ground from the tip and ring conductors of the associated subscribe1"s line as is welllmown in the art. Relay 112 also causes ringing; current to he transmitted 'l'rolu source 124C to call the wanted sul'iscriher. This circuit may be traced as follows: ringing` source 124, lower outer armature and frontcontact of relay 112, eondensenand resistance 125, lower outer armature and haelt contact ol' rclay 105, lower inner armature and l'ront rontact of relay 112, ring' brush R through the ringV conductor ot thc wanted subseril iers line and the loop through his bell back through the tip conductor, tip brush T. upper inner armature and frontcontaet ot relay l 12. third upper armature and back contact of relay 105 to ground. It should he noted that the circuit troni source 12d also extends through the lower winding of relay 105 in parallel with a condenser and resistance 125. Then the called subscriber answers the call by remoring his receiver from the hook the tripping direct current. battery which is supplied dur ing the silent periods at the ringing source 124 will find a path through the lower winding of relay 105 and the subscribers loop to ground so that relay '105 will now operate to trip the ringing. That is, the operation of this relay 105 opens the connection for the above mentioned circuit at the lower outer armature and back contact, and the third upper armature and back contact of this relay. It should be noted that the ringing signal is transmitted through the condenser 127 over the ring conductor to the calling 'sube scribers line, so that he will hear'the calling of the wanted subscriber. Relay 105 in operating provides a locking circuit for itself from battery through its upper winding, upper inner armature and front contact, upper outer armature and front contact of relay 112, to ground at the inner right-hand armature and front contact ofl relay 104.

The operation of relay 105 also extends the connection from the tip and ring conductors from the called subscribers loop at the third upper armature and front contact, and lower outer armature and front cont-act to battery `and ground through the windings of relay 103. This connection is also extended through the condensers'l22 and 130 so that a talking connection will now be completed to the calling subscriber, the battery for the called subscriber being furnished from the battery and ground through the `windings of relay 103. Relay 103 operates in this circuit from the called subscriber to reverse the battery and lground connections through the windings of relay 102 and t-he third and fourth lower armatures and front contacts of.l

relay 103` for calling subscriber supervision.

This battery and ground through the windings of relay 102 furnishes the talking battery for the calling subscriber. The locking. circuits for rela-ys 105 and 112 are now controlled from the ground at the inner lower armature and front contact of relay 103 so that in case the calling subscriber operates his dial to interrupt the circuit for relay 102 it will haveno effect on the established connection.

If the wanted subscriber -is a private branch exchange subscriber the brushes 110 of the connector will advance to the terminal bank 101 to hunt for an idle trunk leading to thedesired private branch exchange in the manner hereinbefore `described in connection with the relation of a wanted subscribers line terminating in bank 100. That is,

brushes 110 willbe advanced to bank 101 and connected with the terminals of the first trunk in this bank. It will be noted that each pair ,of terminals such as S and H of t-he trunks inthe bank 101 are connected together except the corresponding terminals tif and H, for the last trunk. If the first private branch exchange trunk is busy a ground connection will be established to the terminals S `and H of this trunk, anda circuit for relay 118 established as Vhereinbefore y described except that Itheground will be supplied from terminal S. Relay 118.inoperating provides a locking circuit foi-itself ashereinbefore described to the ground at the middle right-hand armature and front contact of relay 101i. v 'A circuit is also established for the release of' relay 116 as follows:

from battery, right-hand winding of relayV erated. A circuit is thereby completed for the operation of the rotary magnet 115 as follows battery, Winding of rotary magnet 115, middle lower armature and back coutact of relay 105, third lower armature and back contact of relay 112, fourth left-hand armature and back contact of relay 116, outer left-hand armature and front contact of relay 118, inner righthand armature and front contact of relay 104. Relay 106 also operates at this time. The operation of the rotary magnet 115 advances brushes 110 to the terminals of the next private Abranch eX- change trunk. Rotary magnet in operating opens the circuit for, relay 118 and this re.- lay in turn opens the circuit for rotary magnet so that the connector will now-` rest with its brushes on the terminals of the second trunk.

If the second trunk is busy relay 118 will again opera-te as soon as rotary magnet 115 is released .and relay -116 is held releasedV through its third left-hand armature Aand back contact The` rotary magnet will therefore continue to operate until an idle trunk is found. Wheuan idle trunk is found relay 118 will not operate and relay 116 will operate, consequently the rotary magnet circuit can notagain be close-d. Due to this condition a circuit will be closed for relay 112 asv follows: battery, through the winding of the usual cut-off relay (not shown) of the idle private. branch exchange trunk through the brush S, outer right-hand armature and back cont-act of relay 106, lower winding of relay 112, inner` left-hand armature and front contact of relay 116, inner left-hand arma-l 124 to be transmitted over the selected pri? vate branch exchange. trunk as hereinbefore.

described and when the `operator at the private branch exchange answers the call the ating causes ringing current from the source loop circuit through her cord circuit causes the tripping relay 105 to be operated to disconnect the ringing and extend the connection to the calling subscriber as hereinbefore described.

Il' all of the trunks connected to the terminals in group 101 are busy the rotary magnet will operate as hereinbelore described to step the brushes 110 from the terminals of one trunk to another until the terminals of the last trunk are reached. 1The terminals S" and H of this trunk are notconnected together. ln this case, however, relay 116 will be maintained released even though there is no ground on the terminal H of this trunk. It will be noted that a circuit under these circumstances will be completed not only for maintaining relay 11G released but also to energize relay 105. This circuit may be traced as follows: battery, right-hand winding of relay 11G, second upper armature and back contact of relay 105, third lett-hand armature and back contact of relay 116, outer left-hand armature and back contact of relay 116, lower winding of relay 105, secondleit-hand armature and back contact ont' relay 110, brush S to ground on terminal S. Ytelay 118 will also be operated through the ground on the S terminal as hereinbe'lfore described to send a busy tone to the calling subscriber. Rotary magnet 115 is thus prevented from operating at this time due to the operation ot relay 105, as its circuit is broken at the middle lower armature and back contact of this relay. Immediately upon the operation of relay 105 relay 116 is permitted to operate as the original circuit for relaysy 105 and 116 as traced above is opened due to the operation of relay 105, but relay 105 is maintained operated over a locking circuit closed on the operation of relay 116 as follows: battery, upper Winding of relay 105, upper inner armature and front Contact of this relay, fourth left-hand armature and front contact of relay 116, outer lefthand armature and front contact of relay 118, inner right-hand armature and front Contact of relay 104: to ground. Hence theringing trip relay 105 is also involved in the stopping of the hunting movement of the rotary magnet 115 when all of the private branch eX- change trunks are busy and the last trunk is reached. y

It' a connection has been established to a subscriber through terminals in either of the groups 100 and 101 and the conversation between the calling subscriber and the called.

subscriber is finished, the connection through the connector and selector may be released by y the called subscriber hanging up his receiver on the hook. Relay 103 will thereby be released to reverse battery and ground through the. windings of relay 102 to release the connection to the calling subscriber. Then this connection is released relays 102 and 104 are released. The release of relay 101 causesthe release ot relays 112 and 105 to return the circuit ot the connector to normal condition.

' lease magnet 132, lower closed contacts of thc vertical oil-normal contacts 10T, iourlh npper armature and back contact oli relay 112, outer right-hand armature and back contact of relay lOl, make-beiorc-breali contacts olf relay 102, to ground. When the connector has returned lo normal, the vertical oit-non mal contacts 10i' will be restored to normal and thus open the circuit for relay lll. The release ot' relay 101 removes the ground l'rom the sleeve brush ot the selector in Fig. 1, .so that relay 12 will now release, to complete the connection for thc release magnet l0 as 'tollows: battery, winding ol release magnet 10,

right-hand armature and bach contact oi. rclay Ll, vertical oil-normal contacts 1l, lower outer armature and hack contact of relay 1;). to ground. 'lhe operation ot release magnet 10 restores the selector to normal condition.

Although the various features olf the invention have been illustrated as applied to one type ol' selector and connector circuits, it is evident that the invention may be applied in many other circuit arrangements without dcparting from the spirit thereof, and that the invention should only be limited by the scope oi the appended claims.

What is claimed is:

1. In a telephone system, a two movement switch, circuits therefor, and a relay in said circuits operated in one manner during the first movement of the switch and operated in another manner during the second movement of the switch to control said second movement.

2. Ina telephone system, a switch having a selectively controlled movement and a hunting movement, circuits therefor, and a relay :tully operated during the selective movement of the switch and partially operated when said selective movement ceases for controlling the hunting movement of the switch.

3. In a telephone system, a switch, a subscribers line, a relay, a signal, means :tor operating Said relay to actuate said signal in response to the seizure of said switch, a ringing current source, means for operating said switchto seize said line, means for releasing said relay for disabling said signal and for applying ringingcurrent from said source to said line, and means responsive When the subscriber 0l' said line answers the call for operating said relay to disconnect the ringing source from the line.

4. In a telephone system, a switch capable of two directive movements, a magnet for directing said switch in one of its movements, a second magnet for directing said switch in its other movement, a relay, means responsive to the seizure ot said switch for operating said relay to disable said second magnet and prelli:

pare said first magnet for its directive operation, and means responsive after the first directing movement of said switch ceases to release said relay to disable the iirst magnet and prepare the second magnet for its .directive operation. n

5. In a telephone system, a switch, a group of trunks terminating in said switch, means for hunting for an idle trunk in said group, a source ot' ringing current, means for stopping the hunting movement of the switch when an idle trunk is found and for transmitting ringing current from said source to said trunk, a relay operated in response to the seizure of the selected trunk at the distant end tor removing the ringing current from said trunk, and means foroperatingsaid relay to stop the trunk hunting movement of the switch on the terminals of the last `trunk of the group, if all of said trunks are thelines in the selected group are busy for transmitting a busy tone from said source to said incoming line. v f v,

7 In a telephone system, a two-movement switch, a pulsing relay to control the first movement of the switch, ya slowto release relay actuated in response to the operation oi' the pulsing relay, means for locking said relay during the two movements of the switch, andanother relay actuated in one manner during the iirst movement `ot the switch and in another manner to control the second movement ot' the switch.

8. In a telephone system, a selector switch, a pulsing relay, a vertical movement magnet, a rotary movement magnet, a. slow to release relay actuated when the pulsing relay is operated, means for locking saidrelay in actu-` ated position, during and after pulsing, another relay, meanstor actuating said vertical magnet in accordance with the operation of the pulsing relay and ttor fully operating said .last mentioned relay during pulsing, and

means responsive-,at the ceasing of the pulsing for partially operating said last mentioned relay toprovide a pulsingcircuit for therotary magnet. e In witness whereof, I hereunto subscribe my name this 10th day of June, A. D. 1927.

`BERT snunnAM. 

